The proposed research seeks to clarify the role of importance of salivary and dietary peptides and proteins in caries development in humans. The ability of salivary proteins from individuals exhibiting differing degrees of caries activity to serve as a source of nitrogen for the growth of Streptococcus mutans and other oral microorganisms will be determined. Also, specific salivary anionic and cationic proteins from human whole saliva and dietary proteins will be tested for their growth-promoting capacity. In conjunction with these studies, partially purified proteolytic enzymes from Strep. mutans and other oral streptococci will be used in studies pertaining to hydrolysis of peptides and proteins of dietary and salivary origin. From these studies the specificity of these proteinases toward such types of substrates will be ascertained. This information will contribute importantly to the further understanding of whether peptides and proteins of salivary and dietary origin play more than a passive role in plaque pathogenicity and oral ecology.